Method and apparatus for enhancing discontinuous reception in wireless systems

ABSTRACT

A method of discontinuous reception (DRX) in a wireless transmit receive unit (WTRU) includes the WTRU receiving DRX setting information over a radio resource control (RRC) signal, and the WTRU receiving DRX activation information over medium access control (MAC) signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/924,484, filed Oct. 25, 2007, now U.S. Pat. No. 8,228,829, issuedJul. 24, 2012; which claims the benefit of U.S. Provisional PatentApplication No. 60/863,185, filed Oct. 27, 2006, the contents of whichare hereby incorporated by reference herein.

FIELD OF INVENTION

The present invention relates to wireless communication systems. Moreparticularly, a method and apparatus is disclosed for enhancingdiscontinuous reception (DRX) in wireless systems.

BACKGROUND

A goal of the Long Term Evolution (LTE) program of the Third GenerationPartnership Project (3GPP) is to bring new technology, networkarchitecture, configurations and applications and services to wirelessnetworks in order to provide improved spectral efficiency, reducedlatency, faster user experiences and richer applications and serviceswith less cost. LTE's aim is to create an Evolved Universal TerrestrialRadio Access Network (E-UTRAN).

In an LTE compliant network, discontinuous reception (DRX) operation isused by a wireless transmit/receive unit (WTRU) to save power. DRXallows the WTRU to sleep during regular intervals and wake up atspecific time instances to verify if the network has data for it.

FIG. 1 shows a typical protocol stack architecture for an LTE network inaccordance with the prior art. The system may include a WTRU 102, an eNode-B (eNB) 104 and an access gateway (aGW) 106. A non access stratum(NAS) protocol 108 and a packet data convergence protocol 110 (PDCP) mayreside in the WTRU 102 and the aGW 106 to allow for communicationbetween the devices. A radio resource control (RRC) protocol 112, aradio link control (RLC) protocol 114, a medium access control (MAC)protocol 116 and a physical layer (PHY) 118 may reside in both the WTRU102 and the eNB 104 to allow for communications between those devices.

The RRC protocol 112 may operate in two states: RRC_IDLE andRRC_CONNECTED. While in RRC_IDLE state the WTRU DRX cycle is configuredby signaling over the NAS protocol 108. This state includes systeminformation broadcasts, paging, and cell resection mobility. A WTRU inRRC_IDLE state preferably is allocated an ID number that identifies theWTRU in a tracking area. No RRC protocol context is stored in an eNB.

In the RRC_CONNECTED state, the WTRU may make a connection with anE-UTRAN. The E-UTRAN knows the cell to which the WTRU belongs to so thatthe network can transmit and receive data to/from the WTRU. In theRRC_CONNECTED state, the network controls mobility (handover) and theWTRU conducts neighbor cell measurements. Furthermore, at the RLC/MAClevel, a WTRU can transmit data to, and receive data from, the networkand monitors a control signaling channel for a shared data channel tosee if any transmission over the shared data channel has been allocatedto the WTRU. The WTRU also reports channel quality information andfeedback information to the eNB. A DRX/discontinuous transmission (DTX)period can be configured according to WTRU activity level for powersaving and efficient resource utilization. This is typically undercontrol of the eNB.

The NAS protocol 108 may operate in an LTE_DETACHED state, in whichthere is no RRC entity. The NAS protocol 108 may also operate in anLTE_IDLE state. Also, the NAS protocol 108 may operate in an RRC_IDLEstate, while in LTE_DETACHED state, during which some information may bestored in the WTRU and in the network, such as IP addresses, securityassociations, WTRU capability information and radio bearers. Decisionsregarding state transitions are typically decided in the eNB or the aGW.

The NAS protocol 108 may also operate in an LTE_ACTIVE state, whichincludes an RRC_CONNECTED state. In this state, state transitions aretypically decided in the eNB or the aGW.

DRX may be activated in LTE_ACTIVE state, which corresponds to theRRC_CONNECTED state. Some of the services that would run in theLTE_ACTIVE state are those services generating small packets on aregular basis, such as VoIP. Also, those services generating delayinsensitive bulk packets on an infrequent basis, such as FTP, may run inthe LTE_ACTIVE, as well as those services generating small packets on arare basis, such as presence service.

Based on the characteristics of the aforementioned services, datatransmission/reception may be performed during DRX operation without RRCsignaling. Also, a DRX cycle length should be long enough for batterypower savings. Furthermore, the amount of data transmitted within a DRXcycle should be variable from cycle by cycle. For example, DRX for FTPservice may allow an increase in the amount of data for each DRX cycle.

FIG. 2 shows a DRX signal structure 200 in accordance with the priorart. An active period 202 is the period during when a WTRU'stransmitter/receiver is turned on and a sleep period 204 is the periodduring when a WTRU's transmitter/receiver is turned off. A DRX cyclelength 206 is the time distance between consecutive active period startpositions.

The DRX cycle length 206 may be determined by the network, consideringthe quality of service (QoS) requirements of a service activated in theWTRU. Active period start positions should be unambiguously identifiedby both the WTRU and the eNB.

At an active period start position, the WTRU may monitor an L1/L2control channel during a predefined time interval to see whether thereis incoming data. A length of the active period 202 may be variable,depending on the amount of data to be transmitted during the DRX cycle206. An end position of active period 202 may be explicitly signaled bythe eNB or implicitly assumed after inactivity of the predefined timeinterval. Uplink data transmission can be initiated anytime during thesleep period 204. Active period uplink data transmission may end whenthe uplink transmission is completed.

FIG. 3 is a signal diagram of a two layer DRX signaling scheme 300 inaccordance with the prior art. The two layer method may be used tosupport flexible DRX and includes splitting the DRX signals into highlevel and low level. Referring to FIG. 3, a high level DRX signal 302 iscontrolled by the RRC. The high level DRX interval 306 depends upon thebasic flow requirements of the connection, for example, voice over IP,web browsing, and the like. The high level DRX interval 306 ispreferably determined by the RRC in the eNB and is signaled to the WTRUusing RRC control signaling.

A low level DRX signal 304 is signaled by the MAC layer. A low level DRXinterval 308 is flexible and may support fast changes in the DRXinterval. A MAC header may carry information regarding low levelsettings.

Dependence between the high level DRX 302 and low level DRX 304 shouldbe at a minimum because the high level DRX interval 306 can be used asfallback DRX interval in case of any errors occur applying the lowerlevel DRX interval 308. The network and the WTRU preferably aresynchronized with the high layer DRX interval 306.

The relatively long high level DRX interval 306 is beneficial for WTRUpower savings, but limits downlink (DL) scheduling flexibility andthroughput. If there is a significant amount of data buffered in an eNBor WTRU transmission buffer, it may be beneficial to change the shortlow level DRX interval 308 for a period of time suitable for thetransmission of the buffered data. After the data transmission, the WTRUand the eNB could resume the high level DRX interval 302.

As shown in Table 1, DRX may be split between regular signals andinterim signals.

TABLE 1 Active mode DRX control signaling RRC MAC Regular DRX control XInterim DRX control X

Signaling DRX in the RRC is based on the regularity of the basicconnection requirements and may result in a regular DRX signal ensuringthe requirements of the connection. Regular DRX is determined in theeNB. A WTRU should know, through RRC signaling, to apply regular DRX. Inother words, when a WTRU enters active mode, one of the RRC parametersdelivered to the WTRU will be the regular DRX parameters to be applied.While in active mode the eNB can change, at any point in time andthrough RRC signaling, the regular DRX parameters used by the WTRU.

FIG. 4 shows RRC signaling for regular DRX 400 in accordance with theprior art. An eNB 406 transmits an RRC signal 404 to a WTRU 402. The RRCsignal 404 includes a regular DRX request. The WTRU 402 responds to theeNB 406 with an RRC signal 408 indicating that the WTRU received theregular DRX request.

MAC layer DRX may be able to handle fast and irregular changes such as,for example, an instantaneous increase of data throughput. The MAC layerinterim DRX may be temporary. Interim DRX settings preferably aredetermined in the eNB. A WTRU acquires information regarding whichinterim DRX parameters to apply through MAC signaling. MAC signalingfrom the eNB to the WTRU may include interim DRX information. The WTRUmay apply the interim DRX according to network instructions. Applyinginterim DRX does not affect the regular DRX interval. When a WTRU nolonger applies interim DRX it will resume regular DRX.

FIG. 5 shows MAC signaling 500 for regular DRX in accordance with theprior art. An e Node-B 506 transmits a MAC signal 504 to a WTRU 502. TheWTRU 502 responds to the eNB 506 with a hybrid automatic retransmitrequest (HARQ) process 508.

SUMMARY

A method and apparatus for discontinuous reception (DRX) in a wirelesstransmit receive unit (WTRU) is disclosed. The method preferablyincludes a WTRU receiving DRX setting information over a radio resourcecontrol (RRC) signal, and the WTRU receiving DRX activation informationover medium access control (MAC) signal. The method may also include theWTRU grouping DRX setting information into a DRX profile and determininga DRX profile index associated with the DRX profile. The method may alsoinclude the WTRU, in a DRX minimum active period, receiving a dataindication signal from an eNB and remaining in an active period based onthe data indication signal.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example and to be understood in conjunction with theaccompanying drawings wherein:

FIG. 1 shows a typical protocol stack architecture for an LTE network inaccordance with the prior art;

FIG. 2 shows a DRX signal structure in accordance with the prior art;

FIG. 3 is a signal diagram of a two layer DRX signaling scheme inaccordance with the prior art;

FIG. 4 shows regular DRX signaling in accordance with the prior art;

FIG. 5 shows interim DRX signaling in accordance with the prior art;

FIG. 6A shows DRX settings information signaling in accordance with oneembodiment;

FIG. 6B shows DRX activation information signaling in accordance withone embodiment;

FIG. 7 a is a signal diagram of DRX operation in accordance with oneembodiment;

FIG. 7 b is a signal diagram of DRX operation in accordance with analternative embodiment;

FIG. 7 c is a signal diagram of DRX operation in accordance with anotherembodiment; and

FIG. 7 d is a signal diagram of DRX operation in accordance with yetanother embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” includes but is not limited to a user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a computer, or any othertype of user device capable of operating in a wireless environment. Whenreferred to hereafter, the terminology “base station” includes but isnot limited to a Node-B, a site controller, an access point (AP), or anyother type of interfacing device capable of operating in a wirelessenvironment.

Two layer DRX operation may include a regular DRX operation controlledby RRC signaling and an interim DRX operation controlled by MACsignaling. The use of RRC signaling takes advantage of the reliabilityand robustness of RRC signaling in general. Reliability is achieved viaresponse or acknowledgement messages that are generated at the RRC layeror via the use of the acknowledged mode (AM) service of the RLC layer.Also, ciphering and integrity protection are required for RRC signaling,thus making an RRC signal a reliable signal.

A MAC signal is used for speed. MAC signaling is generally faster togenerate and to process than RRC signaling. Interim DRX operations thatuse MAC signaling may be flexible, but do not include the reliabilityand security aspects that are provided in RRC signaling and not MACsignaling.

DRX signaling information can be classified into two categories: 1) DRXsettings, parameters or configurations, such as DRX cycle periodicity,for example, and 2) DRX activation commands, such as to turn DRX on oroff, for example.

The DRX settings, parameters or configuration information is preferablysignaled reliably, robustly and securely. Interim DRX RRC signalingparameters and configuration information may be communicated via RRCsignaling. However, DRX activation commands that, for example, instructthe WTRU to enter DRX mode, are preferably signaled quickly via MACsignaling. For example, the commands to enter or exit interim DRX aresignaled via MAC signaling.

In an alternative, some DRX settings, parameters, or configurationinformation may be signaled with the DRX activation commands.

FIG. 6A shows interim DRX setting signaling in accordance with oneembodiment. Interim DRX setting information may be conveyed using RRCmessages. A WTRU 602 receives an RRC signal 606 containing interim DRXsetting information from an eNB 604. The WTRU 602 may respond to the eNB604 with a confirmation signal 608.

FIG. 6B shows interim DRX activation signaling in accordance with oneembodiment. The interim DRX activation signals are conveyed using MACsignals. The WTRU 602 receives a MAC signal 610 containing interim DRXactivation information from an eNB 604. The WTRU 602 may respond to theeNB 604 with a hybrid automatic repeat request (HARQ) signal 612.

Sets of DRX setting information can be grouped to form a DRX profile. ADRX Profile ID may be used to indicate the DRX profile. RRC signalingmay be used to define a DRX profile and attach it to a DRX Profile ID.The DRX profile may be used with interim DRX, regular DRX, or any otherDRX mode. Once the profiles are setup or preconfigured, an eNB and aWTRU may exchange DRX activation commands that may reference anappropriate DRX Profile ID for the WTRU. The activation commands may beRRC signals, but are preferably MAC signals.

The WTRU may dynamically apply the DRX parameter information in aparticular DRX profile using MAC signaling that makes reference to theDRX profile ID, rather than having to specify and detail all DRXparameters. An interim DRX activation signal may reference a DRX ProfileID, or may contain some DRX settings that were not included in the RRCsignaling. This signaling method may be applied to any level DRX or anytype of DRX operation in general.

A DRX cycle may contain an active period and a sleep period. The activeperiod start positions may be unambiguously identified by both a WTRUand an eNB, while the active period length may be variable and depend onan amount of data to be transmitted during the DRX cycle.

A DRX signaling message may specify an activation time or a start timethat is used to indicate a time to activate the DRX cycle or enter intoDRX mode. An activation time can be indicated in absolute terms, orrelative to the present time, to ensure that the both the WTRU and theeNB unambiguously identify the start of the DRX cycle. MAC or RRCsignaling messages used for DRX may include a DRX activation or starttime.

A WTRU may remain in an awake DRX mode for a minimum active period. Theminimum active period preferably is communicated in a DRX signalingmessage, either RRC or MAC, or it can be predefined. The minimum activeperiod may be used for a number of activities. For example, it may beused to increase DRX flexibility, increase DRX robustness, or ensurethat if a WTRU has missed some transmissions it will stay awake toreceive them in an expedited manner.

DRX structure may be defined periodically, for example, one DRX cycleevery 50 msec. In order to increase the flexibility of DRX, another modeof DRX operation may be utilized whereby a DRX cycle start time isdefined during a previous DRX cycle. This mode can be used independentof, or in addition to, the periodic mode of DRX operation. As anexample, during the active period of a DRX cycle, once the WTRU hasreceived its intended data and there are no further packets to transmitto that WTRU at the eNB, the eNB may instruct the WTRU via a signalingmessage, either MAC or RRC, to go to sleep for a predetermined timeand/or wake up at a predetermined time.

Additionally, it may be advantageous under certain circumstances to keepthe WTRU awake during a DRX cycle instead of allowing it to go to sleepuntil the next DRX cycle. In order to achieve that, a DRX signalingmessage, either MAC or RRC, may be used to instruct the WTRU to stayawake until a specified time, such as, the next DRX cycle, for example.

A WTRU may, by default, enter DRX once it is in the active/connectedstate. As an alternative, signaling messages may be used to exchangecapability information regarding whether the WTRU supports DRX operationin the active/connected state. An eNB may obtain the WTRU's active modeDRX capability and any other parameters associated with such capability.Accordingly, the eNB may instruct the WTRU to go into active mode DRX asit deems necessary.

A WTRU may remain awake for a minimum active period. During this period,the eNB may use Layer 1, Layer 2 or Layer 3 signaling messages toindicate whether data will be transmitted to the WTRU during aparticular DRX cycle. The WTRU may stay in the active period until thebeginning of the next DRX cycle. The WTRU will not sleep following thereception of its data until the beginning of the next DRX cycle.

The WTRU may wait for an explicit signal from the eNB to indicate thepresence of data for a particular WTRU. IF the WTRU does not receive anindication from the eNB, the WTRU may determine that no signal wastransmitted or the signal went missing but shall stay awake becausethere might be something on the downlink for the WTRU

FIG. 7A shows a signal diagram for DRX operation 700 in accordance withone embodiment. The DRX cycle 704 includes a minimum active time 710 anda sleep time 702. The WTRU may receive a command 708 in each minimumactive time 710. If data is available for the WTRU, the WTRU receives anindication in the command 708, receives the data 712, and stays awakeuntil the next DRX cycle 704.

In an alternative embodiment, if the eNB has not or will not transmitdata for the WTRU during this DRX cycle, it does not send the command708. The WTRU may interpret the lack of command as an indication that itcan go back to sleep until the next DRX cycle, as it has no data toreceive.

FIG. 7B shows a signal diagram for DRX operation 720 in accordance withanother embodiment. The WTRU receives a command 708 during the minimumactive time 710 indicating whether there is data for the WTRU. Once theWTRU receives the command that indicates that the eNB is transmittingduring the DRX cycle 712, the WTRU exits DRX completely and maydisregard its prior DRX operation and configuration. The WTRU may thenstay awake in a non-DRX cycle 722. The eNB may use a signaling message724 to instruct the WTRU to go back into DRX operation at time 726. Thesignaling can be RRC, MAC, or PHY signaling, and a trigger to generatethe signaling can be the detection of idle or inactivity time followinga data transmission. Another trigger may be the eNB's knowledge thatthere are no more packets that need to be transmitted to the WTRU. TheWTRU then resumes DRX operation and receives a command 708 during thenext minimum active time 710 in the next DRX cycle 704.

FIG. 7C shows a signal diagram for DRX operation 740 in accordance withan alternative embodiment. The DRX signaling message that is used toactivate DRX operation 744 may include a periodicity of the DRX cycle;that is, a DRX cycle time), a minimum active time, and a relative or/andabsolute time when the WTRU should start or activate the DRX operation.The WTRU may go back into DRX operation at the next DRX cycle, as inFIG. 7B, or after the next DRX cycle occurs, as in FIG. 7C.

A WTRU that is not in DRX mode may send a signaling message to an eNBindicating that the WTRU wants to enter DRX mode. The signaling can beRRC, MAC, or PHY signaling. The WTRU may use a trigger to generate thesignaling, such as, the detection of an idle time or inactivity timefollowing the reception of data by the WTRU, for example. There may beother triggers as well. Upon receiving the signaling message, the eNBgenerates a response signal to instruct the WTRU to go into DRXoperation and the DRX settings.

FIG. 7D shows a signal diagram for DRX operation 760 in accordance withanother alternative embodiment. A signaling message 762 indicates arelative or absolute time 764 when data transmission will begin andoptionally, a relative or absolute time when data transmission will end766. The WTRU stays in DRX mode.

A DRX cycle is typically associated with a single WTRU. However, formultimedia broadcast/multicast service (MBMS), it is difficult tobroadcast to multiple WTRUs that have different DRX cycles. Therefore,an eNB or a radio access network (RAN) may define an “MBMS DRX” cyclethat is common for a group of WTRUs. One-to-one signaling messages canbe exchanged between the eNB and a WTRU to set up and confirm the MBMSDRX cycle. In an alternative embodiment, the MBMS DRX cycle can be setup via multicast or broadcast messages, for example, on a broadcastchannel. In another alternative embodiment, the MBMS DRX cycle can beimplicit or derived from a predetermined MBMS scheduling pattern. A WTRUmay power down its MBMS transceiver during an MBMS DRX cycle.

It is preferable to coordinate between the MBMS traffic or the MBMS DRXcycle and the WTRU's normal DRX cycle. For example, MBMS traffic can bescheduled with the DRX cycle of the WTRU. This scheme may be lessflexible if there are many WTRUs involved in MBMS that have differentDRX cycles, but may lead to increased efficiency since the WTRU willhave aligned DRX and MBMS intervals.

During DTX, a WTRU transmits during pre-determined intervals, and sleepsduring the rest. Coordination between DTX and DRX may be utilized, andthe DRX and DTX intervals/cycles may coincide as much as possible, inorder to allow maximum efficiency in power consumption. For example,uplink resource assignment can be performed periodically. Aligning theuplink resource assignment with the DRX period may result in greaterefficiency. In particular, periodic thin channel assignments cancoincide with the DRX cycle.

System messages related to handover are critical. If a DRX cycle is toolong, a WTRU may react too late to handover commands, which can causecomplete failure of transmission and reception. Accordingly, thehandover timing should be a consideration when the DRX cycle isdetermined, adjusted and signaled by an eNB.

For example, when a WTRU is close to a cell edge a measurement cycle maybe required to be shorter than the normal DRX cycle in LTE active mode.Therefore, a signaling message may be sent to the WTRU to reconfigurethe DRX cycle to reflect the WTRU being close to a cell edge.

Additionally, when a neighbor cell's measurements are strong, meaning itis a high probability that handover may occur, the DRX cycle should beturned off by the eNB by sending a signaling message or command to theWTRU. The WTRU may continuously monitor its own and its neighbor cell'sreference signal, to, for example, prepare autonomous timing adjustment,or to prepare for any handover related activity. In general, when theserving cell's signal strength or transmission quality indicator isbelow a certain threshold, the WTRU preferably is not be put into DRXmode in order to give the WTRU a better chance to make measurements andtry and sustain the call.

WTRU mobility aspects may also be a factor in determining the DRX cyclein LTE active mode. Separate DRX settings may be implemented fordifferent services, such as VoIP, web browsing traffic and the like. AWTRU may have multiple separate or independent DRX cycles for each ofthe services, or a WTRU may have a single DRX cycle whose DRXsettings/parameters satisfy the most frequent traffic pattern. Ifmultiple DRX cycles are used, the cycles may be aligned or coincide asmuch as possible, in order to maximize the potential for power savings.

Although the features and elements are described in the embodiments inparticular combinations, each feature or element can be used alonewithout the other features and elements of the embodiments or in variouscombinations with or without other features and elements. The methods orflow charts provided may be implemented in a computer program, software,or firmware tangibly embodied in a computer-readable storage medium forexecution by a general purpose computer or a processor. Examples ofcomputer-readable storage mediums include a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) module.

What is claimed:
 1. A method implemented by a wireless transmit receiveunit (WTRU) for performing discontinuous reception (DRX) while in anRRC_CONNECTED state, the method comprising: the WTRU receiving DRXsetting information from an evolved Node-B (eNB) via a radio resourcecontrol (RRC) message, the DRX setting information indicating a lengthof a minimum active period, wherein the minimum active periodcorresponds to a minimum amount of time during which the WTRU is activeat a beginning of a given DRX cycle; the WTRU monitoring for receptionof Layer 1 control signaling from the eNB during the minimum activeperiod of a first DRX cycle, wherein the Layer 1 control signalingindicates whether data is to be transmitted to the WTRU; the WTRUreceiving a data indication message during the minimum active period ofthe first DRX cycle, the data indication message indicating thatdownlink data is to be transmitted to the WTRU; the WTRU remaining in anawake state beyond the minimum active period of the first DRX cyclebased on receiving the data indication message; while awake, the WTRUreceiving a DRX activation medium access control (MAC) message; and theWTRU resuming DRX operation in response to receiving the DRX activationMAC message.
 2. The method of claim 1, wherein the data indicationsignal is received via Layer 1 control signaling.
 3. The method of claim1, further comprising the WTRU receiving the downlink data after stayingawake in response to receiving the data indication message.
 4. Themethod of claim 3, wherein the downlink data is received from the eNB ona shared data channel.
 5. The method of claim 1, wherein the WTRUinterprets lack of receipt of the Layer 1 control signaling during theminimum active period of the first DRX cycle as an indication that theWTRU may go to sleep at an end of the minimum active period of the firstDRX cycle.
 6. The method of claim 5, further comprising the WTRU wakingup at the start of a subsequent DRX cycle to monitor for reception ofsubsequent Layer 1 control signaling.
 7. The method of claim 6, furthercomprising the WTRU determining that the subsequent Layer 1 controlsignaling was not received during a minimum active period of thesubsequent DRX cycle.
 8. The method of claim 7, further comprising theWTRU going to sleep until a beginning of a next DRX cycle based ondetermining that the subsequent Layer 1 control signaling was notreceived during the minimum active period of the subsequent DRX cycle.9. The method of claim 8, wherein the trigger for sending the DRXactivation MAC message to the WTRU is the eNB determining that there arecurrently no more packets that need to be transmitted to the WTRU. 10.The method of claim 1, wherein the DRX setting information furtherindicates a DRX cycle periodicity.
 11. The method of claim 1, furthercomprising the WTRU receiving a periodic allocation for a thin channel,wherein transmission using the periodic allocation of the thin channelare configured to coincide with active periods of DRX cycles.
 12. A basestation for facilitating discontinuous reception (DRX) at a wirelesstransmit receive unit (WTRU), the base station comprising a processorconfigured, at least in part, to: send DRX setting information to theWTRU using a radio resource control (RRC) message, the DRX settinginformation indicating a length of a minimum active period, wherein theminimum active period corresponds to a minimum amount of time duringwhich the WTRU is active at a beginning of given DRX cycle; send a dataindication signal to the WTRU using Layer 1 control signaling, whereinthe Layer 1 control signaling is used to indicate whether or not the eNBwill transmit download data to the WTRU during the given DRX cycle; sendthe downlink data to the WTRU after transmitting the data indicationsignal; and send a DRX activation medium access control (MAC) message tothe WTRU, wherein the DRX activation MAC message indicates that the WTRUis to resume DRX.
 13. The base station of claim 12, wherein theprocessor is configured to send the DRX activation MAC message to theWTRU based on a determination that the base station does not currentlyhave any remaining packets to be transmitted to the WTRU.
 14. The basestation of claim 12, wherein the processor is configured to send thedownlink data to the WTRU using a shared data channel.
 15. The basestation of claim 12, wherein the DRX setting information furtherindicates a DRX cycle periodicity.
 16. The base station of claim 12,wherein failure to send the Layer 1 control signaling to the WTRU duringthe minimum active period indicates that the WTRU may go to sleep at anend of the minimum active period until a start of a subsequent DRXcycle.
 17. A wireless transmit receive unit (WTRU) comprising aprocessor configured, at least in part, to: receive DRX settinginformation from the eNB in a radio resource control (RRC) message, theDRX setting information indicating a length of a minimum active periodand a DRX cycle periodicity, wherein the minimum active periodcorresponds to a minimum amount of time during which the WTRU isconfigured to be active at a beginning of given DRX cycle; monitor forreception of Layer 1 control signaling from the eNB during the minimumactive period of a first DRX cycle, wherein the Layer 1 controlsignaling indicates whether or not the eNB will transmit download datato the WTRU during the first DRX cycle, and the WTRU is configured tointerpret lack of receipt of the Layer 1 control signaling during theminimum active period of the first DRX cycle as an indication that theWTRU may go to sleep at an end of the minimum active period of the firstDRX cycle; receive a data indication message during the minimum activeperiod of the first DRX cycle, the data indication message indicatingthat downlink data is to be transmitted to the WTRU; remain in an awakestate beyond the minimum active period of the first DRX cycle based onreceiving the data indication message; receive a DRX activation mediumaccess control (MAC) message; and resume DRX operation in response toreceiving the DRX activation MAC message.
 18. The WTRU of claim 17,wherein the processor is configured to receive the data indicationsignal via Layer 1 control signaling.
 19. The WTRU of claim 17, whereinthe processor is further configured to receive the downlink data on ashared data channel after staying awake in response to receiving thedata indication message.
 20. The WTRU of claim 17, wherein the processoris configured to awaken the WTRU at the start of a subsequent DRX cycleto monitor for reception of subsequent Layer 1 control signaling. 21.The WTRU of claim 20, wherein the processor is further configured to:determine that the subsequent Layer 1 control signaling was not receivedduring a minimum active period of the subsequent DRX cycle; and put theWTRU to sleep until a beginning of a next DRX cycle based on determiningthat the subsequent Layer 1 control signaling was not received duringthe minimum active period of the subsequent DRX cycle.
 22. The WTRU ofclaim 17, wherein the processor is further configured to receive aperiodic allocation for a thin channel, wherein transmissions using theperiodic allocation of the thin channel are configured to coincide withactive periods of DRX cycles.
 23. A wireless transmit receive unit(WTRU) comprising a processor configured, at least in part, to: receiveDRX setting information from the eNB in a radio resource control (RRC)message, the DRX setting information indicating a length of a minimumactive period, wherein the minimum active period corresponds to aminimum amount of time during which the WTRU is configured to be activeat a beginning of given DRX cycle; monitor for reception of Layer 1control signaling from the eNB during the minimum active period of afirst DRX cycle, the Layer 1 control signaling indicating whetherdownlink data will be transmitted to the WTRU, receive a data indicationmessage during the minimum active period of the first DRX cycle, thedata indication message indicating that downlink data is to betransmitted to the WTRU, remain in an awake state beyond the minimumactive period of the first DRX cycle based on receiving the dataindication message, receive a DRX activation medium access control (MAC)message, and resume DRX operation in response to receiving the DRXactivation MAC message.
 24. The WTRU of claim 23, wherein the processoris configured to receive the data indication signal via Layer 1 controlsignaling.
 25. The WTRU of claim 23, wherein the processor is furtherconfigured to receive the downlink data on a shared data channel afterstaying awake in response to receiving the data indication message. 26.The WTRU of claim 23, wherein the WTRU is configured to interpret notreceiving the Layer 1 control signaling during the minimum active periodof the first DRX cycle as an indication that the WTRU may go to sleep atan end of the minimum active period of the first DRX cycle.